1. Field of the Invention
The present invention relates to a chip type electric double layer capacitor and a method for manufacturing the same, and more particularly, to a chip type electric double layer capacitor having an external terminal of which portions exposed to a bottom of an internal space and the outside of a lower case are integrally connected to each other, and a method for manufacturing the same.
2. Description of the Related Art
Stable energy supply is an important factor in various electronic products such as information and communication equipment. Generally, this function is performed by a capacitor. That is, the capacitor plays a role of collecting and discharging electricity and stabilizing an electricity flow in a circuit of the information and communication equipment and the various electronic products. The general capacitor has a short charging and discharging time, a long life, and a high output density, but it has a limitation to be used as a storage device due to a low energy density.
In order to overcome this limitation, recently, a new category of capacitors such as an electric double layer capacitor having a short charging and discharging time and a high output density has been developed and is in the spotlight with a secondary battery.
The electric double layer capacitor, as an energy storage device using a pair of charge layers (electrode layers) of different polarities, is capable of continuously charging and discharging and has advantages of energy efficiency, output, durability, and stability in comparison with other general capacitors. Accordingly, recently, the electric double layer capacitor, which is capable of high current charging and discharging, is promising as an electrical storage device having high charging and discharging frequency such as an auxiliary power supply for mobile phones, an auxiliary power supply for electric vehicles, and an auxiliary power supply for solar cells.
The electric double layer capacitor has a basic structure composed of an electrode with a relatively large surface area such as a porous electrode, electrolyte, a current collector, and a separator. The electric double layer capacitor employs an electrochemical mechanism generated when ions in the electrolyte move along an electric field and are absorbed on a surface of the electrode by applying several bolts of voltage to both ends of the unit cell electrode, as an operation principle.
A general method to surface-mount this electric double layer capacitor on a circuit board is to surface-mount the electric double layer capacitor on the circuit board through brackets by welding the brackets to upper and lower parts of the electric double layer capacitor.
However, a thickness of the electric double layer capacitor of this structure is relatively large and increased by additional structures (brackets and the like) required for surface-mounting. In case of using this electric double layer capacitor, there is a difficulty in manufacturing a high capacity product due to increase in thickness, and further, that is a product price rise factor due to additional processes.